An Egyptian security official says ousted president Hosni Mubarak has slipped in the bathroom in the prison where is serving a life sentence, hitting his head.

The official says the ailing Mubarak, 84, was treated in Cairo’s Tora prison Saturday for head injuries and a chest bruise. He says Mubarak slipped before two months ago but did not injure himself.

The report comes at a particularly tense moment in the transition that has followed Mubarak’s 2011 overthrow, as millions of Egyptians vote in a highly contentious referendum on a draft constitution written by a mostly Islamist panel.

Mubarak was convicted of failing to stop killings of protesters during the uprising. There have been conflicting reports about his health.